Insulation types

Loft insulation is the easiest way households can reduce their carbon footprint and save money at the same time, but unfortunately too many of us stop there

While other forms of insulation besides loft insulation can be more difficult to install, the rewards can be greater — but with so many different types of insulation available how do you know what is best for your property?

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Cavity wall insulation is perhaps the best known and applies to a lot of newer properties. If your house was built between 1920 and 2000, your home probably has cavity walls, meaning a space between the inner and outer walls.

Cavity wall insulation prices start from £450, but it will also save you around £140 a year on your energy bills, so you can expect it to pay for itself in four years or less. However, it isn’t something you can do yourself, and requires a certified installer drilling small holes into your outer walls and pumping in the insulation.

Solid wall insulation

While many of us are familiar with cavity wall insulation, where the space between the inner and outer wall is insulated, few of us consider solid wall insulation. However, it is hard to imagine a more effective form of energy-saving than solid wall insulation, quite simply because solid walls let through two times more heat than cavity walls.

The first thing to determine is whether you have solid walls on your property. The single best indicator is age.

If your house was constructed prior to 1920, there is a good chance it is solid wall. If this is the case, you can insulate the inner and outer walls.

The Energy Saving Trust estimates that installing inner wall insulation on a typical gas-heated semi-detached home could save you £460 a year, but with costs of between £5,500 and £8,500 it could be a fair while until you’ve repaid the initial outlay.

External wall insulation could save you slightly more — £490 a year — but it costs more too, with installation costs ranging from £9,400 to £13,000.

Of the two types of solid wall insulation, inner wall is the cheaper to install, but there are some compromises. It consists of fixing insulation to the wall with render placed over the top, so it will reduce the available space in the room by bringing each wall inwards by about 100 mm.

The installation process also requires you to remove things like skirting boards, door frames and external fittings, which are the then reattached. This can then make it difficult to attach heavy items to the walls (although there are ways around this).

External wall insulation

External wall insulation is a slightly different proposition and comes with its own advantages and disadvantages. The benefits are that it won’t reduce inner room size, and can also be installed without you having to empty rooms for any period of time.

It can also improve weathering and sound-proofing of your home, and can reduce draughts by plugging in any gaps between bricks.

The main disadvantage to external wall insulation is the cost which can be significant, but there are ways you can reduce the financial burden.

Your best bet is to only consider external wall insulation as part of a wider refurbishment project, such as fitting a new kitchen or bathroom. Not only can you then combine the logistical hassle but, by installing insulation one room at a time, you can spread the cost of insulation.

Similarly, if you are having a larger piece of work done to the exterior of your home, such as getting a new roof or painting, then you will save money on costs like scaffolding.

It is also worth noting that you may need to check with your local council to see whether you need planning permission.

Underfloor insulation

Underfloor insulation is the next logical step for those who have already covered their loft and walls. And those who have done some draught proofing.

Under floor insulation is typically installed on the ground floor, or in upper-floor rooms above unheated areas. And while the savings are much more modest — an estimated £60 a year according to the Energy Saving Trust — the costs of installing under floor insulation are far lower, too.

Some things can be done yourself like filling in any gaps, particularly around skirting boards, but if you have timber floors you can insulate them.

Timber floors are most commonly found in older properties, and a layer of mineral wall or other suitable insulation materials underneath the timber will keep the heat in. Installation costs will vary from very little if you are doing it yourself to around £500 if you are calling in the experts.

Concrete floor insulation is more difficult to do yourself, so is best combined with having the floor replaced, or you can place a layer of rigid insulation on top.

The insulation is placed on top of the concrete and a layer of chipboard covers the insulation, but be aware that concrete floor insulation will raise your floor level slightly, so watch out for door frames, skirting boards or sockets that may need to be raised.

Pipe insulation

Pipe insulation, which is typically combined with insulation of the hot water cylinder, is very cheap and easy to do, and will usually pay for itself in a year.

If your pipes are easy to reach it is as simple as covering your pipes with pre-fitted pipe insulation from your DIY store, and keeping your hot water hot for longer.

Pipe insulation materials come in all different shapes in sizes, so just make sure to take accurate measurements of your pipes width and length. Insulating your hot water tank costs slightly more (around £15 for a jacket), but pays for itself in half a year. Even if your tank already has insulation fitted, you should check to make sure it is 75 mm thick at least.

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